In the semiconductor fabrication field, wafers tend to increase in size every year, and become thinner to improve package density. Generally, the surface protective tape for protecting the semiconductor element is attached on the front surface of the wafer, and then a back grinding process is conducted in which the back surface of the semiconductor wafer is ground to reduce the wafer thickness.
When the back grinding process is completed, as shown in FIG. 17, a dicing film 3 is attached on the back surface 22 of the wafer 20, so that the wafer 20 and an annular mount frame 36 can be integrated with each other.
Then, as shown in FIG. 18, the wafer 20 is held on table 131 with surface protective film 11 located above. In the process, an annular part of the adhering surface 3a of the dicing film 3 is exposed between the mount frame 36 and the wafer 20. Then, by supplying peeling tape 4 onto attaching member 146 and pressing attaching member 146 against the surface protective film 11, the peeling tape 4 is attached to the surface protective film 11. Then, table 131 for supporting the wafer 20 is moved in a horizontal direction. Since the portion where the peeling tape 4 is attached functions as a peeling start point, with the result that the surface protective film 11 can be peeled off continuously from the wafer 20 starting with the peel starting point.
As shown in FIG. 18, the forward end of the attaching member 146 is pressed against the surface protective film 11 while being placed diagonally downward with respect to the horizontal surface. However when supplying the peeling tape 4, the peeling tape 4 at the forward end 146a of the attaching member 146 may loosen and form a loop 4′, thereby adhering to the adherent surface 3a (In this connection, the wafer 20 and the surface protective film 11 are actually considerably smaller in thickness than the attaching member 145).
In addition, the adherent surface of the peeling tape 4 and the adherent surface of the dicing film 3 attach to each other. The film 3 and the tape 4, once adhered to each other, are very difficult to separate without damaging the wafer 20. A similar problem may be also occur in the case where the section of the attaching member 146 is not triangular but circular, for example.
Japanese Unexamined Patent Publication No. 2005-311176 discloses that a groove extending beyond the width of the peeling tape is formed along the outer periphery of the wafer on the table. This groove is formed in a region having no holding function.
When the wafer is placed on the table and held, the air in the groove is also sucked through the gap between the dicing film and the table. While the upper part of the groove is closed by the dicing film, the air in the groove is sucked through the gap located above the groove. As a result, the internal pressure of the groove becomes negative, and the dicing film partially enteres and collapses into the groove. In such a case, even if a loop is formed by the peeling film, the loop does not reach the dicing film, and therefore, the peeling tape 4 is prevented from attaching to the dicing film.
However, in Japanese Unexamined Patent Publication No. 2005-311176, the groove does not have the holding function. Therefore, when holding the wafer, the dicing film is not necessarily collapsed in the groove and there may be a case in which the dicing film is not fully collapsed into the groove. In such a case, the loop of the peeling tape may attach to the dicing film.
Further, in Japanese Unexamined Patent Publication No. 2005-311176, cancellation of holding of the wafer causes air to flow into the groove through the gap between the dicing film 3 and the table. However since the dicing film 3 is formed of a soft material, the complete cancellation of the negative pressure of the groove is not guaranteed even after the cancellation of holding of the wafer, and the negative pressure of the groove may hamper the recovery of the mount frame. Furthermore, the dicing film may be deformed and not restored to the original position. In such a case, easily handling of the wafer is reduced in the subsequent steps.
Further, according to Japanese Unexamined Patent Publication No. 2005-311176, the side surfaces of the groove are formed substantially perpendicular to the surface of the table. The dicing film 3, collapsed in the groove, may be considerably deformed, and may not be restored to the original position. Further, the wafer, which is reduced considerably in thickness by back grinding, may be pulled and may break when the dicing film 3 is dented.
Furthermore, the die attach film (not shown), which is divided together with the wafer 20 at the time of dicing, may be attached to the dicing film 3. In such a case, the adhering strength of the dicing film 3 increases, and therefore, the possibility of the peeling tape 4 attaching to the dicing film 3 further increases.
This invention has been achieved in view of this situation, and the object thereof is to provide a wafer table and a surface protective film peeling apparatus and a surface protective film peeling method using the wafer table, in which the dicing film is positively collapsed into the groove and can be restored to the original position.